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Biomedical subjects

V Hombach

Publications and source records attributed to V Hombach.

At least 145 records · Page 8Linked to original sources
PubMed1992

[Diagnosis of cardiac arrhythmias in general practice].

Cardiac arrhythmias represent a common diagnostic and a frequent therapeutic problem (table 1). They occur both in cordially sound people and in patients with a basic cardiac disease, their clinical significance reaching, therefore, from harmless to life-threatening episodes. For this reason, a documentation and characterization of the different arrhythmias is necessary in clinical practice in order to be able to initiate an adequate therapy in symptomatic and particularly in prognostically relevant cardiac arrhythmias.

Arrhythmias, Cardiac↗
PubMed1992

[Determination of normal values of the aortic blood flow profile using continuous Doppler echocardiography from apical and suprasternal echo position].

The present study was undertaken to measure normal aortic blood velocity profiles by means of continuous wave Doppler echocardiography from apical and suprasternal positions in 40 healthy adults. The profiles in the ascending aorta were measured from both positions, whereas the profiles in the descending aorta were measured only from the suprasternal position. The highest values for the maximal flow velocities were found in the ascending aorta from the suprasternal position (1.28 +/- 0.18 m/s), the lowest values for the maximal flow velocities were found in the descending aorta (1.17 +/- 0.22 m/s). This trend was also found for the mean velocity values. As to the time parameters, a longer acceleration time for the descending aorta was remarkable (106 +/- 24 ms), whereby the mean values for the ejection time for the descending aorta (308 +/- 25 ms, suprasternal: 320 +/- 30 ms). The highest values for the acceleration were found in the ascending aorta (suprasternal: 1526 +/- 531 cm/s2, apical: 1422 +/- 330 cm/s2) and the lowest values in the descending aorta (1208 +/- 378 cm/s2). Regarding the maximal velocity index there was no significant difference for the maximal values between the different transducer positions. The results of the regression analysis showed only a weak correlation of the maximal velocity values in the different transducer positions. This means that for follow-up examinations only those values should be used that were obtained from the same transducer position.

Adult↗
PubMed1992

[Quantification of tricuspid insufficiency--comparison of Doppler echocardiography and radionuclide ventriculography].

In 40 patients (pts) (ages 34-83 years) the severity of tricuspid regurgitation (TR) was graded by pulsed Doppler echocardiographic determination of regurgitant jet extension. Mild TR was assessed in seven pts (group I), mode-rate TR in 20 pts (group II), and severe TR in 13 pts (group III). The enddiastolic diameter of the left ventricle as measured by M-mode-echocardiography was 55 +/- 16 mm in group I, 48 +/- 6 mm in group II, and 50 +/- 10 mm in group III. The regurgitant index (RI), i.e., the ratio of left-to-right-ventricular stroke counts (normal range 0.89-1.97) and the time-activity curve over the liver area were measured by equilibrium radionuclide ventriculography (RNV). The RI differed significantly between group I (1.6 +/- 0.5), II (1.0 +/- 0.3), and III (0.8 +/- 0.3) (p less than 0.01). An RI-value below 0.89 as an index of right-ventricular volume overload was found in 14% (group I), 45%, (group II) and 77% (group III). The time-activity curve over the liver area, as graded by count variation in phase with the right atrium from 1 (no count variation) to 4 (typical count variation) showed all grades in groups I and II, but only grade 2 to 4 in group III. The RI resp. the time-activity curve over the liver is a sensitive parameter for the detection of moderate to severe TR. If TR is ascertained, severe regurgitation can be differentiated from mild regurgitation by RNV-derived RI as an index of right-ventricular volume overload.

Adult↗
PubMed1992

Short-term reproducibility of gas exchange measurements during bicycle exercise in patients with mild to moderate congestive heart failure.

A series of 45 patients with congestive heart failure due to coronary disease had semisupine bicycle exercise tests (ramp protocol, 10 W/min) on two occasions separated by 3 to 7 days in order to determine the short-term reproducibility of gas exchange measurements during symptom-limited exercise. The percentage difference (PD) between each pair of measurements (m1, m2; PD = 100%.(m2-m1): m1) were calculated. The mean PD values (+/- 1 sigma) and the single determination standard deviations (SDSD) for exercise tolerance (ET, W), peak heart rate (pHR, 1/min), peak oxygen uptake (pVO2, ml/min/kg), peak carbon dioxide output (pVCO2, ml/min/kg), and peak minute ventilation (pVE, l/min) were as follows: [table: see text] No patient reached a plateau of oxygen uptake during the last portion of the ramp exercise test. Thus, pVO2 is not an objective endpoint. The single determination standard deviations show that exercise tolerance and peak oxygen uptake do not differ as to their reproducibility. The absolute values of PD were not a function of exercise tolerance for any of the parameters studied. The PD values for ET and pVO2 were normally distributed. The data suggest that a change in ET and pVO2 must exceed 27% and 28% between two sequential studies in an individual patient in order to be significant at the 5% level, respectively. For the one-tailed test situation, the changes in ET or pVO2 must be greater than 23% in order to be significant.

Adult↗
PubMed1991

Effects of atenolol, slow-release nifedipine, and their combination on respiratory gas exchange and exercise tolerance in stable effort angina.

The effects of atenolol, nifedipine, and their combination on gas exchange and exercise tolerance were studied in 27 patients with effort angina and normal global ventricular function in an open-label and randomized cross-over trial. Symptom-limited semi-supine exercise tests using a ramp protocol (20 W/min) with simultaneous breath-by-breath analysis of gas exchange were carried out after a 4-day wash-out period and after consecutive 2-week treatment periods with atenolol (50 mg b.i.d.), slow-release nifedipine (20 mg b.i.d.), and their combination (b.i.d.). Exercise tolerance was not significantly higher with atenolol than with nifedipine [118(24) vs 113(23) W]. Combination therapy [120(23) W] was more effective than monotherapy with nifedipine (p less than 0.05) but produced no further increase in exercise tolerance over atenolol monotherapy. Maximum oxygen uptake was not significantly different among the treatments. In the range of light to moderate exercise, the slope of the VO2-workload regression line expressed as ml.min-1.W-1 was lower with atenolol than with nifedipine [8.64(1.59) vs 10.28(1.74), p less than 0.005] and intermediate with combination therapy [9.99(1.83)]. The intercept on the VO2 axis was higher with atenolol than with nifedipine [366(111) vs 299(113) ml.min-1, p less than 0.05]. A similar pattern of results was seen when the drug effects on the slope of the VCO2-workload relation were analyzed. VE was higher with nifedipine than with atenolol at all points of the regression analysis [greater than 30 W].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Reproducibility of quantitative hexakis-2-methoxyisobutylisonitrile single photon emission tomography in stable coronary artery disease.

The quantification of myocardial perfusion abnormalities is necessary to allow comparison of repeated studies, especially in the evaluation of the success of medical, interventional or combined treatment in stable coronary artery disease or in evolving myocardial infarction. The purpose of this study was to assess inter-observer reproducibility of tomographic study processing using a semi-automatic quantitative programme. Technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-Sestamibi) was chosen for tomographic imaging of repeated rest-stress studies in patients with stable coronary artery disease. The quantification was performed using a modification of the Cedars polar coding and comparison with the normal data base. The perfusion defects were quantified separately for each standard perfusion area [left anterior descending (LAD), right coronary (RCA) and left circumflex (LCX) arteries] and total area of hypoperfused myocardium. The inter-observer variability for 40 tomographic studies was accomplished. The defects were the largest in the LAD perfusion area (average 19.7% of the normalized LAD supply area) with an inter-observer correlation of 0.84 for this region. The greatest variability was found for the LCX region (r = 0.55) and is attributed to a small average perfusion defect (7.1%), only 18 studies having abnormal perfusion in this area. In total, an average 14.3% of the left ventricular myocardium was significantly hypoperfused, and the inter-observer correlation was 0.87. These results show good inter-observer reproducibility using semi-automatic quantitation of perfusion defects. Careful interpretation of smaller defects in the evaluation of treatment results is advised when repeated 99mTc-Sestamibi single photon emission tomography studies are processed by more than one observer.

Coronary Disease↗
PubMed1991

Comparison of once daily felodipine 10 mg ER and hydrochlorothiazide 25 mg in the treatment of mild to moderate hypertension.

The efficacy of extended release felodipine 10 mg (ER) o.d., a new dihydropyridine calcium antagonist, and 25 mg hydrochlorothiazide (HCTZ) o.d. have been compared in a randomized, double-blind, crossover trial in 28 mildly to moderately hypertensive subjects (supine diastolic blood pressure, BP, greater than or equal to 95 mm Hg and less than or equal to 110 mm Hg on three separate occasions). Both drugs significantly reduced systolic and diastolic BP in the sitting position felodipine from 157.1/93.8 mm Hg at baseline to 133/78.9 mm Hg 2.5 h after medication and to 138/82.7 mm Hg after 2 weeks of treatment, and HCTZ from 156/95.6 mm Hg to 147/88.4 mm Hg 2.5 h after medication and to 149/89.5 mm Hg also after 2 weeks. A decrease of the same magnitude in standing systolic and diastolic BP was observed after both treatment regimens with the exception of diastolic BP 2.5 h after dosing with HCTZ, which was not significantly lower. At all times (2.5 h and 2 weeks), the reduction in systolic and diastolic BP was greater after felodipine compared to HCTZ. Heart rate was significantly increased after felodipine in both the sitting and standing positions, and both 2.5 h following medication and after 2 weeks of treatment. The difference between the regimens was significant only 2.5 h after dosing. Overall, felodipine 10 mg ER o.d. was superior to 25 mg HCTZ o.d. in lowering BP.

Administration, Oral↗
PubMed1991

Localization of ectopic ventricular depolarization by ISPECT-radionuclide ventriculography and by magnetocardiography. ISPECT and MCG for ectopic mapping.

Since catheter or surgical techniques for ablating the arrhythmogenic substrate in patients with SVT due to accessory pathways or those with VT are now available, exact localization of the substrate is mandatory. We report preliminary results of two new non-invasive techniques for localizing either the site of earliest ventricular contraction using ISPECT, or the site of initial ventricular depolarization by magnetocardiography (MCG) in WPW syndrome and in VT patients. Thirteen patients with WPW syndrome and 8 patients with sustained VTs were studied with ISPECT. In 9/13, comparative catheter mapping data were available. Two patients had two Kent bundles. 13/15 Kent bundles could be localized by ISPECT. In 5/9 patients the area of Kent bundle insertion was identical with ISPECT and catheter mapping, in 3 correlation was fair, and in 2 patients with 2 Kent bundles ISPECT failed to localize their insertion. In 3/8 patients with VT catheter mapping could not be performed for hemodynamic reasons. In 2/5 patients the area of VT focus was identical with both methods, in one patient it was adjacent to each other, and in 2/5 patients a larger anatomic distance of the focus was found with both methods. In 3/7 patients with WPW the MCG showed the site of Kent bundle insertion, which was identical to that seen by catheter mapping. In one patient the area was adjacent, and in 3 more distant from the site determined by catheter mapping. In 1/2 patients with 2 Kent bundles, one of these could be detected by MCG. In 1/3 patients with VT, the site of VT focus was identical with both methods, but in the remaining two a distance of 3-4 cm was observed between the area seen with MCG and that with catheter mapping. In 4 further VT patients with stable and uniform ventricular late potentials, ventricular late magnetic activity was found with different QRS lengths within the single MCG channels. From our results we conclude that both ISPECT and MCG seem to become very promising non-invasive techniques for localizing ectopic ventricular depolarization in WPW syndrome and VT patients. However, these methods have to be refined, improved and validated by further systematical studies.

Action Potentials↗
PubMed1991

Standards for analysis of ventricular late potentials using high-resolution or signal-averaged electrocardiography: a statement by a task force committee of the European Society of Cardiology, the American Heart Association, and the American College of Cardiology.

Sufficient data are available to recommend the use of the high-resolution or signal-averaged electrocardiogram in patients recovering from myocardial infarction without bundle branch block to help determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available about the extent to which pharmacological or nonpharmacological interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be resolved. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase.

Analog-Digital Conversion↗
PubMed1991

Association between plasma viscosity and blood pressure. Results from the MONICA-project Augsburg.

The relationship between determinants of blood viscosity and blood pressure (BP) variables was studied in a large sample of a population aged 25 to 64 years. Plasma viscosity, hemoglobin, and total serum protein were examined. Systolic and diastolic BP and the prevalence of hypertension showed a crude positive association with plasma viscosity levels in both sexes. Age, body mass index, and total serum protein appeared to have a confounding effect on this relationship, whereas hemoglobin, smoking behavior, and alcohol consumption did not. A crude positive association was also found between total serum protein levels and the prevalence of hypertension in men and women; however, since total serum protein was treated as a covariable, no further analyses were carried out. In contrast to findings reported in the literature, hemoglobin levels were not correlated with BP variables in either sex. After adjusting for all confounders, a significant main effect of plasma viscosity still was found. However, the magnitude of the effect was not as large as for body mass index, a well-established risk variable for hypertension. These results indicate that BP is positively associated with plasma viscosity. Whether increased plasma viscosity in hypertension constitutes a primary or a secondary phenomenon remains to be answered. Since plasma viscosity is significantly associated with hypertension but any BP variable, increased levels of plasma proteins (particularly fibrinogen as the main determinant of plasma viscosity) may represent the cause for elevated plasma viscosity. This might contribute to persistently increased resistance to blood flow on the microcirculatory level in arterial hypertension.

Adult↗
PubMed1991

Chemical ablation by subendocardial injection of ethanol via catheter--preliminary results in the pig heart.

This study was set up to discover how a subendocardial application of ethanol administered via a catheter would affect an animal model. A 7 F bipolar catheter with a lumen, through which a 2 mm needle was inserted, was placed in the left ventricle of 11 pigs. Altogether, 33 subendocardial injections into the left ventricular myocardium were performed under fluoroscopic control using a mixture of 0.5-1.5 ml ethanol and 0.5-1 ml iopamidol as contrast medium. The mixtures were injected into the apical, lateral and septal walls of the left ventricle. After 25 days, the hearts were removed and the lesions examined pathologically. The calculated volume of the lesions was about 60 mm3, the area in projection to the endocardium about 35 mm2, the depth relative to the endocardium about 1.5 mm and the maximum diameter about 8 mm. Perforation of the myocardial wall by pericardial injection occurred twice without further complications. Subendocardial application of concentrated ethanol by catheter caused a controlled local necrosis. This technique may become a new approach with which to treat ventricular tachycardia by chemical ablation.

Animals↗
PubMed1991

Standards for analysis of ventricular late potentials using high resolution or signal-averaged electrocardiography. A statement by a Task Force Committee between the European Society of Cardiology, the American Heart Association and the American College of Cardiology.

Sufficient data are available to recommend that the high-resolution or signal-averaged electrocardiogram can be used in patients recovering from myocardial infarction without bundle branch block to help to determine their risk for developing sustained ventricular tachyarrhythmias. However, no data are available regarding the extent to which pharmacologic or non-pharmacologic interventions in patients with late potentials have an impact on the incidence of sudden cardiac death. Therefore, controlled, prospective studies are required before this issue can be definitely answered. As refinements in techniques evolve, it is anticipated that the clinical value of high-resolution or signal-averaged electrocardiography will continue to increase in the future.

Arrhythmias, Cardiac↗
PubMed1991

Catecholamines and the renin-angiotensin-aldosterone system during treatment with felodipine ER or hydrochlorothiazide in essential hypertension.

The neurohumoral responses after 10 mg of felodipine extended release (ER), a new dihydropyridine calcium antagonist, and 25 mg of hydrochlorothiazide (HCTZ) were compared in a randomized, double-blind, crossover trial in 28 mild to moderate hypertensives. Antihypertensive drugs were gradually discontinued. Felodipine ER, 10 mg was given once daily for 2 weeks; after another washout period of 1 week, patients were switched to 25 mg of HCTZ once daily and vice versa. Blood pressure (BP) was measured at baseline, 2.5 h after medication, and after 2 weeks of treatment (24 h postdosing) using an oscillometric device. Felodipine ER and HCTZ both lowered BP effectively. However, felodipine ER was superior in reducing systolic and diastolic BP during the short term and medium term. Treatment with felodipine ER over 2 weeks increased sympathetic outflow as indicated by elevated plasma norepinephrine levels, whereas plasma epinephrine was mainly unaffected, as were plasma renin and aldosterone levels. On the other hand, 25 mg of HCTZ increased plasma renin and aldosterone, but left catecholamines unchanged. Despite persistent increased sympathetic activity, the reduction in BP in this study was more pronounced after felodipine ER as compared to HCTZ. The lack of a difference between heart rates under both medications after 2 weeks of treatment suggests a resetting of the baroreflex by felodipine ER and furthermore that the increased norepinephrine levels may not be clinically relevant, but demonstrate the maintained baroreflex activity. HCTZ, in doses as low as 25 mg, is still capable of stimulating the renin-angiotensin-aldosterone system.

Adult↗
PubMed1991

Left ventricular function and wall thickness in long-term insulin-dependent diabetes mellitus: an echocardiographic study.

Left ventricular function and wall thickness were evaluated in 111 type I diabetic subjects (mean age 25.5 +/- 9 years, mean duration of diabetes 13.4 +/- 6.2 years), using 2-D-derived M-mode echocardiography. Patients were carefully selected for the absence of major coronary risk factors or manifest cardiac disorders, and compared with 91 age- and sex-matched control subjects. Fractional shortening and the maximal velocity of cirumferential fibre shortening did not differ significantly between the two groups. Furthermore, no differences were found in the diastolic functional parameter of velocity of circumferential fibre extension. Posterior wall thickness was significantly increased in the diabetic patients compared to the controls (9.5 +/- 1.8 mm vs. 8.4 +/- 1.3 mm. P less than 0.01). As the thickness of the interventricular septum was also moderately increased (9.2 +/- 2.2 mm vs. 8.9 +/- 1.7 mm, NS), these findings provide evidence for an early structural change of the myocardium in young diabetic patients without clinically relevant functional consequences.

Adult↗
PubMed1991

Effects of felodipine ER and hydrochlorothiazide on blood rheology in essential hypertension--a randomized, double-blind, crossover study.

The haemorheological effects of felodipine extended release (ER), a new dihydropyridine calcium antagonist, were compared with hydrochlorothiazide (HCTZ) in 28 mild to moderate hypertensives (18 men and 10 women, aged 30-70 years) in a randomized, double-blind, crossover trial. Antihypertensive drugs were gradually discontinued. Felodipine Er, 10 mg, was given once daily for 2 weeks, and after another wash-out period of 1 week, patients were switched to 25 mg HCTZ, once daily, and vice versa. Whole blood viscosity (BV) at three different shear stresses, haematocrit (Hct), plasma viscosity (PV), red blood cell (RBC) aggregation, RBC deformability, and fibrinogen were measured under standardized conditions 2.5 h after medication, and after 2 week of treatment (24 h post-dosing). Felodipine ER improved BV acutely, but not during treatment over a 2-week period. By contrast, HCTZ did not affect BV, but decreased RBC deformability 2.5 h after medication intake. After 2 weeks of treatment, the negative effect on RBC deformability had increased slightly. Furthermore, fibrinogen and PV were significantly elevated at this stage. In summary, felodipine ER did not improve blood rheology over a 2-week treatment period in this study. HCTZ exhibited marginal but significant negative effects on fibrinogen, PV and indices of RBC deformability, but not on RBC aggregation.

Adult↗
PubMed1991

Diastolic ventricular function in type 1 diabetic patients: a study using Doppler echocardiography.

The transmitral flow velocity pattern of 28 Type 1 diabetic patients and 39 age-matched healthy control subjects was studied for determination of left ventricular diastolic function. No patient had systemic hypertension, congestive heart failure, or ischaemic heart disease by clinical or electrocardiographic criteria. Echocardiographic measures of systolic ventricular function were within normal range in all subjects. The ratio of early to late transmitral peak flow velocity (ve/va) was significantly decreased in the diabetic patients (1.3 +/- 0.1 (+/- SE) vs 1.6 +/- 0.1, p less than 0.05), while other Doppler derived variables did not show any significant difference. No correlation of ve/va with duration of diabetes was found (r = -0.27), but it correlated with age in both groups (both r = -0.40, p less than 0.05). Furthermore, a significant correlation was found between ve/va and heart rate (r = -0.55 for diabetic patients, p less than 0.01; r = -0.58 for control subjects, p less than 0.01). After matching for heart rate (24 diabetic patients and 24 control subjects) no significant decrease of ve/va was observed in the diabetic group.

Adult↗
PubMed1991

Biomagnetic noninvasive localization of accessory pathways in Wolff-Parkinson-White syndrome.

It was our purpose to assess the clinical relevance of noninvasive magnetocardiographic localization of accessory pathways. Nine patients with Wolff-Parkinson-White (WPW) syndrome were studied. For all of them the site of the accessory pathway was known from invasive catheter mapping. A 37-SQUID (superconducting quantum interference device) sensor multichannel system (KRENIKON) was used, allowing synchronous registration with all channels. The site of the electrophysiological activity at the beginning of the delta wave was determined. Magnetic resonance images of the heart were obtained to correlate the biomagnetically localized activity with the anatomy. Magnetocardiographic localization of the bypass tract corresponded with catheter mapping with a spatial difference of 0-5 cm, 1.8 cm on the average, compared to the results obtained by catheter mapping. Thus, magnetocardiography is a promising new method for noninvasive localization of accessory pathways in WPW patients. This may streamline further invasive procedures.

Adult↗